In traditional mining, slurry pipeline systems are built with significant reservoir capacity to maintain a steady flow rate. Oil sands slurry pipeline systems have limited reservoir capacity and as a result may have a highly variable flow rate. The flow rate may be increased or decreased for a variety of reasons depending on, for instance, changing upstream availability of oil sands slurry as well as other process operating constraints.
Enabling efficient flow of a slurry, such as oil sands slurry, through a pipeline also requires some operating conditions that are not normally required for other liquids. For instance, it is desirable to maintain an adequate flow rate in the pipeline when operating at low flow rates to avoid “sanding off”, which is when some of the oil sands normally suspended in the solvent come out of suspension thereby hindering the flow and increasing wear on pipeline equipment.
Variable flow rate slurry flowing downhill in undulating terrain, such as in an oil sands mine, thus requires a smaller pipeline diameter in order to maintain adequate line pressure during times of reduced flow rate. Unfortunately, using a smaller pipeline diameter results in excessive pipeline wear and system energy loss at normal or high flow rates. Current industry practice is to accept the energy loss and install sacrificial wear components such as reduced line size sections, orifice plates or valves.
Oil sands mining and transportation are also fraught with harsh conditions and oils sands slurry can be more damaging on pipeline equipment than other fluids and suspensions traditionally transported by pipeline.
There is currently a need for a technology that overcomes at least one of the disadvantages of what is currently known and used in the field.